Here's another reason why a healthy diet during pregnancy is critical to the future health of your children: New research published in the March 2013 issue of The FASEB Journal, suggests that pregnant mothers who consume junk food actually cause changes in the development of the opioid signaling pathway in the brains of their unborn children. This change results in the babies being less sensitive to opioids, which are released upon consumption of foods that are high in fat and sugar. In turn, these children, born with a higher "tolerance" to junk food need to eat more of it to achieve a "feel good" response.